The present invention relates to a method for making oleochemical oil-based polyols using acid treated clay catalysts. The oleochemical oil-based polyols can be used to produce polyurethane resins for a variety of uses.
Polyols may be produced from petroleum. However, polyols made from oleochemical oils would be preferred since they come from renewable resources. Oleochemical oils are produced from the fats and oils of, for example, beef tallow, palm oil, lard, castor oil, peanut oil, rapeseed oil, cottonseed oil, soya bean oil, sunflower oil, and linseed oil. Oleochemical oil molecules must be chemically transformed in order to introduce hydroxyl groups. For instance, soybean oil does not contain any hydroxyl groups but has on an average about 4.6 double bonds per molecule. The unsaturated portions of the vegetable oil molecule can be converted to hydroxyl groups. However, many reactions for preparing polyols from vegetable oils are not very selective. By-products, in addition to alcohol groups, are created during the transformation. Furthermore, many conventional methods of preparing polyols from vegetable oil do not produce polyols having a significant content of hydroxyl groups, and many available methods of preparing polyols from vegetable oils do not produce products having a desirable viscosity. Greases or waxes often result as a consequence of such chemical transformations.
Vegetable oil-based polyols are known. For example, U.S. Pat. No. 6,107,433 to Petrovic, et al. discloses a process for converting vegetable oil into polyols by epoxidizing the oil using a fluoboric acid catalyst and then hydroxylating the epoxidized oil to a polyol using more fluoboric acid catalyst plus an alcohol or an alcohol and water, which is preferred. The problem with the process is that the fluoboric acid is expensive, highly reactive, hazardous to handle, and highly exothermic, must be quenched, and its byproducts present disposal problems. The polyols can be used to make polyurethane resins.
Polyurethane resins prepared with castor oil have also been produced. However, these resins tend to be rubbery and thus undesirable for certain casting applications. Still further, castor oil-based polyurethanes have some limitations due to their higher price and environmental problems related to their by-products. For example, U.S. Pat. No. 4,508,853 to Kluth, et al. teaches the preparation of polyurethane prepolymers containing terminal isocyanate groups in which oleochemical polyols are present as the polyol component. The polyols are made by subjecting epoxidized triglycerides to ring opening using acid catalysis such as mineral acids, including sulfuric acid, phosphoric acid, hydrochloric acid, or organic acids such as sulfonic acids, including p-toluene sulfonic acid. Other examples of urethanes incorporating fatty polyols made by acid catalyzed hydroxylation of epoxidized fatty acids includes U.S. Pat. No. 4,546,120 to Peerman, et al.; U.S. Pat. No. 4,551,517 to Herold, et al.; U.S. Pat. No. 4,742,087 to Kluth, et al.; U.S. Pat. No. 4,826,944 to Hoefer, et al.; U.S. Pat. No. 4,886,893 to Meffert, et al.; U.S. Pat. No. 5,266,714 to Stoll, et al.; and U.S. Pat. No. 5,302,626 to Hoefer, et al.
The use of clay catalysts is known. For example, U.S. Pat. Nos. 5,750,787 and 5,672,752 to Lai, et al. teach the use of clay catalysts in a process for monoalklating diphenylamine. U.S. Pat. No. 4,474,602 to Markley, et al. teaches the use of clay catalysts in a process for making substituted pyridyl compounds. U.S. Pat. No. 4,133,799 to R. W. Layer teaches the use of clay catalysts to catalyze the reaction of glyoxal with phenols.
In order to overcome the deficiencies found with conventional processes for making oleochemical oil-based polyols, a method for making oleochemical oil-based polyols from epoxidized oleochemical oil is needed for a variety of applications including preparation of, through polyurethane chemistry, of resins for a variety of uses.